Nanowire transistor fabrication with hardmask layers

ABSTRACT

A nanowire device of the present description may be produced with the incorporation of at least one hardmask during the fabrication of at least one nanowire transistor in order to assist in protecting an uppermost channel nanowire from damage that may result from fabrication processes, such as those used in a replacement metal gate process and/or the nanowire release process. The use of at least one hardmask may result in a substantially damage free uppermost channel nanowire in a multi-stacked nanowire transistor, which may improve the uniformity of the channel nanowires and the reliability of the overall multi-stacked nanowire transistor.

CROSS REFERENCES TO RELATED APPLICATIONS

The present Application is a Continuation Application of U.S. patentapplication Ser. No. 16/149,056 filed Oct. 1, 2018, which is aDivisional Application of U.S. patent application Ser. No. 13/996,850filed Jun. 21, 2013, now U.S. Pat. No. 10,121,861, issued on Nov. 6,2018, which is a 371 National Stage Entry of International ApplicationNo. PCT/US2013/031943, filed on Mar. 15, 2013, the entire contents ofwhich are incorporated herein by reference.

TECHNICAL FIELD

Embodiments of the present description generally relate to the field ofnanowire microelectronic devices, and, more particularly, to a nanowirestructure formed using at least one hardmask to prevent degradation ofnanowire channels during fabrication.

BACKGROUND

Higher performance, lower cost, increased miniaturization of integratedcircuit components, and greater packaging density of integrated circuitsare ongoing goals of the microelectronic industry for the fabrication ofmicroelectronic devices. As these goals are achieved, themicroelectronic devices scale down, i.e. become smaller, which increasesthe need for optimal performance from each integrated circuit component.

Maintaining mobility improvement and short channel control asmicroelectronic device dimensions scale down past the 15 nanometer (nm)node provides a challenge in microelectronic device fabrication.Nanowires may be used to fabricate microelectronic devices which provideimproved short channel control. For example, silicon germanium(Si_(x)Ge_(1-x)) nanowire channel structures (where x<0.5) providemobility enhancement at respectable Eg, which is suitable for use inmany conventional products which utilize higher voltage operation.Furthermore, silicon germanium (Si_(x)Ge_(1-x)) nanowire channels (wherex>0.5) provide mobility enhanced at lower Egs (suitable for low voltageproducts in the mobile/handheld domain, for example).

Many different techniques have been attempted to fabricate and sizenanowire-based device. However, improvements may still be need in thearea of fabricating uniform nanowire channels.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification.The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. It is understoodthat the accompanying drawings depict only several embodiments inaccordance with the present disclosure and are, therefore, not to beconsidered limiting of its scope. The disclosure will be described withadditional specificity and detail through use of the accompanyingdrawings, such that the advantages of the present disclosure can be morereadily ascertained, in which:

FIGS. 1-14 are oblique and cross-sectional views of a process of forminga nanowire transistor, according to an embodiment of the presentdescription.

FIGS. 15 and 16 are oblique views of a process of forming a nanowiretransistor, according to another embodiment of the present description.

FIG. 17 is a flow chart of a process of fabricating a microelectronicdevice, according to an embodiment of the present description.

FIG. 18 illustrates a computing device in accordance with oneimplementation of the present description.

DESCRIPTION OF EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings that show, by way of illustration, specificembodiments in which the claimed subject matter may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the subject matter. It is to be understood thatthe various embodiments, although different, are not necessarilymutually exclusive. For example, a particular feature, structure, orcharacteristic described herein, in connection with one embodiment, maybe implemented within other embodiments without departing from thespirit and scope of the claimed subject matter. References within thisspecification to “one embodiment” or “an embodiment” mean that aparticular feature, structure, or characteristic described in connectionwith the embodiment is included in at least one implementationencompassed within the present description. Therefore, the use of thephrase “one embodiment” or “in an embodiment” does not necessarily referto the same embodiment. In addition, it is to be understood that thelocation or arrangement of individual elements within each disclosedembodiment may be modified without departing from the spirit and scopeof the claimed subject matter. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of thesubject matter is defined only by the appended claims, appropriatelyinterpreted, along with the full range of equivalents to which theappended claims are entitled. In the drawings, like numerals refer tothe same or similar elements or functionality throughout the severalviews, and that elements depicted therein are not necessarily to scalewith one another, rather individual elements may be enlarged or reducedin order to more easily comprehend the elements in the context of thepresent description.

In the production of nanowire transistors, a replacement gate processmay be utilized, which requires removing of a sacrificial gate electrodematerial formed over a fin structure comprising layers of sacrificialmaterials and channel gate material layers. The removal of thesacrificial gate electrode may be followed by removal of sacrificialmaterials from between channel gate material layers to form a pluralityof stacked channel nanowires, known as a “nanowire release process”. Theremoval of the sacrificial materials in either the replacement gateprocess or the nanowire release process may be achieved with etchingprocesses, such as a dry etch, a wet etch, a combination of oxidationand wet etch, and the like. With regard to dry etching, the uppermostchannel nanowire may be damaged more by ion bombard than the otherchannel nanowires (either plasma or plasmaless processes), as exposureto the ion bombardment is greater on the uppermost channel nanowire.With regard to the wet etch and the combination of oxidation and wetetch processes, the uppermost channel nanowire may be damaged more thanthe other channel nanowires, as the uppermost channel nanowire will havethe longest exposure time to the oxidation and/or etching chemicals.Thus, the removal processes may result in an uppermost channel nanowirewhich is less uniform and less reliable than other channel nanowires inthe transistor.

Embodiments of the present description include the incorporation of atleast one hardmask during the fabrication of at least one nanowiretransistor in order to assist in protecting an uppermost channelnanowire from damage that may result from fabrication processes, such asthose used in a replacement metal gate process and/or the nanowirerelease process. The use of at least one hardmask may result in asubstantially damage free uppermost channel nanowire in a multi-stackednanowire transistor, which may improve the uniformity of the channelnanowires and the reliability of the overall multi-stacked nanowiretransistor.

FIGS. 1-14 illustrate methods of forming a nanowire transistor. For thesake of conciseness and clarity, the formation of a single nanowiretransistor will be illustrated. As illustrated in FIG. 1 , amicroelectronic substrate 110 may be provided or formed from anysuitable material. In one embodiment, the microelectronic substrate 110may be a bulk substrate composed of a single crystal of a material whichmay include, but is not limited to, silicon, germanium,silicon-germanium or a Ill-V compound semiconductor material. In otherembodiments, the microelectronic substrate 110 may comprise asilicon-on-insulator substrate (SOI), wherein an upper insulator layercomposed of a material which may include, but is not limited to, silicondioxide, silicon nitride or silicon oxy-nitride, disposed on the bulksubstrate. Alternatively, the microelectronic substrate 110 may beformed directly from a bulk substrate and local oxidation is used toform electrically insulative portions in place of the above describedupper insulator layer.

As further shown in FIG. 1 , a plurality of sacrificial material layers(illustrated as elements 122 ₁, 122 ₂, and 122 ₃) alternating with aplurality of channel material layers (illustrated as elements 124 ₁, 124₂, and 124 ₃) may be formed by any known technique, such as by epitaxialgrowth, on the microelectronic substrate 110 to form a layered stack126. In one embodiment, the sacrificial material layers 122 ₁, 122 ₂,and 122 ₃ may be silicon layers and the channel material layers 124 ₁,124 ₂, and 124 ₃ may be silicon germanium layers. In another embodiment,the sacrificial material layers 122 ₁, 122 ₂, and 122 ₃ may be silicongermanium layers and the channel material layers 124 ₁, 124 ₂, and 124 ₃may be silicon layer. Although three sacrificial material layers andthree channel material layers are shown, it is understood that anyappropriate number of sacrificial material layers and channel materiallayers may be used.

As shown in FIG. 2 , a hardmask layer 130 may be formed on a top surface125 of the uppermost channel material layer 1243. The uppermost channelmaterial layer 1243 may be defined to be the channel material layerfarthest from the microelectronic substrate 110. The hardmask layer 130may be any appropriate hardmask material, including but not limited tosilicon, porous silicon, amorphous silicon, silicon nitride, siliconoxynitride, silicon oxide, silicon dioxide, silicon carbonitride,silicon carbide, aluminum oxide, hafnium oxide, zirconium oxide,tantalum silicate, lanthanum oxide, polymer materials, and the like. Thehardmask layer 130 may be formed by any technique known in the art,including but not limited to, physical vapor deposition (PVD), atomiclayer deposition (ALD) and various implementations of chemical vapordeposition (CVD), such as atmospheric pressure CVD (APCVD), low pressureCVD (LPCVD), and plasma enhanced CVD (PECVD).

The layered stack 126 (see FIG. 2 ) and the hardmask layer 130 may bepatterned using conventional patterning/etching techniques to form atleast one fin structure 128, as shown in FIG. 3 . For example, thelayered stack 126 (see FIG. 2 ) and the hardmask layer 130 may be etchedduring a trench etch process, such as during a shallow trench isolation(STI) process, wherein trenches 144 may be formed in the microelectronicsubstrate 110 in the formation of the fin structure 128, and wherein thetrenches 144 may be formed on opposing sides of the fin structures 128.As will be understood by those skilled in the art, a plurality ofsubstantially parallel of fin structures 128 are generally formedsimultaneously.

As shown in FIG. 4 , dielectric material structures 146, such as silicondioxide, may be formed or deposited within the trenches 144 proximatethe microelectronic substrate 110 to electrically separate the finstructures 128. As will be understood to those skilled in the art, theprocess of forming the dielectric material structures 146 may involve avariety of process including, but not limited to, depositing dielectricmaterial, polishing/planarizing the dielectric material, and etchingback the dielectric material.

As shown in FIG. 5 , spacers 160 may be formed on and across the finstructure 128 and the hardmask layer 130, and may be disposedsubstantially orthogonally with respect to the fin structure 128. In anembodiment, the spacers 160 may comprise any material that may beselective during subsequent processing to the fin structure 128materials and the hardmask layer 130, as will be discussed. As furthershown in FIG. 5 , a sacrificial gate electrode material 152 may beformed within/between the spacers 160, and may be formed around portionsof the fin structures 128 located between the spacers 160. In anembodiment, the sacrificial gate electrode material 152 may be formedaround portions of the fin structure 128 and the hardmask layer 130, andthe spacers 160 may be on either side of the sacrificial gate electrodematerial 152. The sacrificial gate electrode material 152 may compriseany appropriate sacrificial material, including, but not limited topolysilicon. As shown in FIG. 6 , a portion of each fin structure 128and the hardmask layer 130 (external to the sacrificial gate electrodematerial 152 and the spacers 160) may be removed to expose portions 112of the microelectronic substrate 110. The portions of each fin structure128 and the hardmask layer 130 may be removed by any process known inthe art, including, but not limited to, a dry etching process.

As shown in FIG. 7 , a source structure 170 and a drain structure 180may be formed on the microelectronic substrate portions 112 (see FIG. 6) on opposing ends of the fin structure 128, such as by an epitaxialgrowth of silicon or silicon germanium, and may be coupled to theportions of the fin structures 128 disposed between the spacers 160. Inan embodiment, the source structures 170 or the drain structures 180 maybe n-doped silicon for an NMOS device, or may be p-doped silicon/silicongermanium for a PMOS device, depending on the device type for theparticular application. Doping may be introduced in the epitaxialprocess, by implant, by plasma doping, by solid source doping or byother methods as are known in the art.

As shown in FIG. 8 , an interlayer dielectric layer 190 may be formed onthe microelectronic substrate 110 over the source structures 170, thedrain structures 180, the sacrificial gate electrode material 152, andthe spacers 160, wherein the interlayer dielectric layer 190 may beplanarized, such as by chemical mechanical polishing, to expose thesacrificial gate electrode material 152. As shown in FIG. 9 , thesacrificial gate electrode material 152 may then be removed from betweenthe spacer materials 160, such as by an etching process, including butnot limited to a wet etch, a combination of wet etching and oxidation,or a dry etch (plasma or plasmaless).

As shown in FIG. 10 , the sacrificial material layers 122 ₁, 122 ₂, and122 ₃ (see FIG. 9 ) may be selectively removed from the fin structure128 (see FIG. 9 ) between the channel material layers 124 ₁, 124 ₂, and124 ₃ (see FIG. 9 ) to form channel nanowires (illustrated as elements120 ₁, 120 ₂, and 120 ₃, and may be referred to herein collectively as“channel nanowires 120 _(n)”) extending between the source structure 170(see FIG. 7 ) and the drain structure 180, wherein the channel nanowires120 _(n) may be aligned vertically (e.g. z-direction) and spaced apartfrom one another. In an embodiment, the sacrificial material layers 122₁, 122 ₂, and 122 ₃ may be etched with a wet etch, a combination of wetetching and oxidation, or a dry etch (plasma or plasmaless) thatselectively removes the sacrificial material layers 122 ₁, 122 ₂, and122 ₃ while not etching the channel material layers 124 ₁, 124 ₂, and124 ₃. In one embodiment, wherein the sacrificial material layers 122 ₁,122 ₂, and 122 ₃ are silicon and the channel material layers 124 ₁, 124₂, and 124 ₃ are silicon germanium, the wet etch may include, but is notlimited to, aqueous hydroxide chemistries, including ammonium hydroxideand potassium hydroxide. In another embodiment, wherein the sacrificialmaterial layers 122 ₁, 122 ₂, and 122 ₃ are silicon germanium and thechannel material layers 124 ₁, 124 ₂, and 124 ₃ are silicon, the wetetch may include, but is not limited to solutions of carboxylicacid/nitric acid/hydrofluoric acid, and solutions of citric acid/nitricacid/hydrofluoric acid. It is understood that the hardmask layer 130 mayprotect the uppermost channel material layer 124 ₃ during this process.

In an embodiment, both silicon and silicon germanium channel nanowires120 _(n) may exist on the same wafer, in the same die, or on the samecircuit, for example as NMOS Si and PMOS SiGe in an inverter structure.In an embodiment with NMOS Si and PMOS SiGe in the same circuit, the Sichannel thickness (SiGe interlayer) and SiGe channel thickness (Siinterlayer) may be mutually chosen to enhance circuit performance and/orcircuit minimum operating voltage. In an embodiment, the number ofnanowires on different devices in the same circuit may be changedthrough an etch process to enhance circuit performance and/or circuitminimum operating voltage.

As shown in FIG. 11 , the hardmask layer 130 may be removed from betweenthe spacers 160. In one example, wherein the hardmask layer 130comprises silicon nitride, a solution of phosphoric acid may be used forthe removal of the hardmask layer 130. It is also understood that thehardmask layer 130 may be removed during the removal of the sacrificialmaterial layers 122 ₁, 122 ₂, and 122 ₃, but may remain sufficientlylong enough to protect the uppermost channel material layer 124 ₃ duringthe majority of the process.

As shown in FIG. 12 (cross-section along line 12-12 of FIG. 11 ), a gatedielectric material 192 may be formed to surround the channel nanowires120 ₁, 120 ₂, and 120 ₃ between the spacers 160. In an embodiment, thegate dielectric material 192 may comprise a high k gate dielectricmaterial, wherein the dielectric constant may comprise a value greaterthan about 4. Example of high k gate dielectric materials may includebut are not limited to hafnium oxide, hafnium silicon oxide, lanthanumoxide, zirconium oxide, zirconium silicon oxide, titanium oxide,tantalum oxide, barium strontium titanium oxide, barium titanium oxide,strontium titanium oxide, yttrium oxide, aluminum oxide, lead scandiumoxide, and lead zinc niobate. In one embodiment, the gate dielectricmaterial 192 may be formed substantially conformally around the channelnanowires 120 ₁, 120 ₂, and 120 ₃, and may form a substantiallyconformal layer on the spacers 160. The gate dielectric material 192 maybe deposited using any method well-known in the art to yield a conformallayer, such as, but not limited to, atomic layer deposition (ALD) andvarious implementations of chemical vapor deposition (CVD), such asatmospheric pressure CVD (APCVD), low pressure CVD (LPCVD), and plasmaenhanced CVD (PECVD).

As shown in FIGS. 13 and 14 , a gate electrode material 154 may then beformed around the channel nanowires 120 ₁, 120 ₂, and 120 ₃ to form agate electrode 150 and thereby forming a multi-stacked nanowiretransistor 100. The gate electrode material 154 may comprise anyappropriate conductive material, including, but not limited to, puremetal and alloys of titanium, tungsten, tantalum, aluminum, copper,ruthenium, cobalt, chromium, iron, palladium, molybdenum, manganese,vanadium, gold, silver, and niobium. Less conductive metal carbides,such as titanium carbide, zirconium carbide, tantalum carbide, tungstencarbide, and tungsten carbide, may also be used. The gate electrodematerial may also be made from a metal nitride, such as titanium nitrideand tantalum nitride, or a conductive metal oxide, such as rutheniumoxide. The gate electrode material may also include alloys with rareearths, such as terbium and dysprosium, or noble metals such asplatinum.

As shown in FIG. 14 , the nanowire transistor 100 may include thespacers 160 (illustrated as a first spacer 160 ₁ and a second spacer 160₂) positioned proximate opposing ends, first end 162 and second end 164,respectively, of an uppermost channel nanowire 120 ₃ and each abutting atop surface 165 of the uppermost channel nanowire 120 ₃ (i.e., theuppermost channel material layer top surface 125 becomes the uppermostchannel nanowire top surface 165 on the fabrication of the channelnanowires 120 _(n)). A first portion 130 ₁ of the hardmask layer 130 mayreside between the first spacer 160 ₁ and the uppermost channel materiallayer top surface 125, and a second portion 130 ₂ of the hardmask layer130 may reside between the second spacer 160 ₂ and the uppermost channelmaterial layer top surface 125. The gate dielectric material 192 mayabut the uppermost channel nanowire top surface 165 between the hardmasklayer first portion 130 ₁ and the hardmask layer second portion 130 ₂.Further, the gate electrode 150 may abut the gate dielectric material192.

It is understood that further processing, not shown, may be conducted,such as forming trench contacts to the source structure 170 and thedrain structure 180, and the like.

It is understood that plurality of hardmasks may be used. For example,beginning with the layered stack 126 (see FIG. 2 ) with the hardmasklayer 130 formed thereon, at least one additional hardmask layer 132 maybe formed on the hardmask layer 130. The layered stack 126 (see FIG. 2), the hardmask layer 130, and the at least one additional hardmask 132may be patterned using conventional patterning/etching techniques toform at least one fin structure 128, as shown in FIG. 15 . For example,the layered stack 126 (see FIG. 2 ), the hardmask layer 130, and the atleast one additional hardmask layer 132 may be etched during a trenchetch process, such as during a shallow trench isolation (STI) process,wherein trenches 144 may be formed into the microelectronic substrate110 in the formation of the fin structure 128.

As shown in FIG. 16 , dielectric material structures 146, such assilicon dioxide, may be formed or deposited within the trenches 144proximate the microelectronic substrate 110 to electrically separate thefin structures 128. As previously discussed, the process of forming thedielectric material structures 146 may involve a variety of processincluding, but not limited to, depositing dielectric material,polishing/planarizing the dielectric material, and etching back to thedielectric material to form the dielectric material structures 146. Asshown in FIG. 17 , the at least one additional hardmark layer 132 ofFIG. 16 may be eroded, ablated, or removed during these processes, ormay be removed by a separate process thereafter. The processing thencontinues at FIG. 5 , as discussed above. It is understood that whenmore than one hardmask layer is utilized, the at least one additionalhardmask layer 132 may be selected to specifically resist the processwith regard to the formation of the dielectric material structures 146and the hardmask layer 130 may be selected to specifically resist theprocess with regard to the removal of the sacrificial material layers122 ₁, 122 ₂, and 122 ₃.

FIG. 17 is a flow chart of a process 200 of fabricating a nanowiretransistor structure according to an embodiment of the presentdescription. As set forth in block 202, a microelectronic substrate maybe formed. A stacked layer comprising at least one sacrificial materiallayer and at least one channel material layer may be formed on themicroelectronic substrate, as set forth in block 204. As set forth inblock 206, a hardmask layer may be formed on a top surface of thechannel material layer farthest from the microelectronic substrate. Atleast one fin structure may be formed from the layered stack and thehardmask layer, as set forth in block 208. As set forth in block 210, atleast two spacers may be formed across the fin structure. A sacrificialgate electrode material may be formed between the at least two spacers,as set forth in block 212. As set forth in block 214, a portion of thefin structure external to the sacrificial gate electrode material andthe spacers may be removed to expose portions of the microelectronicsubstrate. A source structure and a drain structure may be formed on themicroelectronic substrate portions on opposing ends of the finstructure, as set forth in block 216. As set forth in block 218, aninterlayer dielectric layer may be formed over the source structure andthe drain structure. The sacrificial gate electrode material may beremoved from between the spacers, as set forth in block 220. As setforth in block 222, the sacrificial material layers may be selectivelyremoved from between the channel material layer to form at least onechannel nanowire. The hardmask layer may be removed from between thespacers to leave a portion of the hardmask layer between the spacers anda channel nanowire top surface farthest from the microelectronicsubstrate, as set forth in block 224. As set forth in block 226, a gatedielectric material may be formed to surround the channel nanowirebetween the spacers. A gate electrode material may be formed on the gatedielectric material, as set forth in block 228.

FIG. 18 illustrates a computing device 300 in accordance with oneimplementation of the present description. The computing device 300houses a board 302. The board 302 may include a number of components,including but not limited to a processor 304 and at least onecommunication chip 306. The processor 304 is physically and electricallycoupled to the board 302. In some implementations the at least onecommunication chip 306 is also physically and electrically coupled tothe board 302. In further implementations, the communication chip 306 ispart of the processor 304.

Depending on its applications, the computing device 300 may includeother components that may or may not be physically and electricallycoupled to the board 302. These other components include, but are notlimited to, volatile memory (e.g., DRAM), non-volatile memory (e.g.,ROM), flash memory, a graphics processor, a digital signal processor, acrypto processor, a chipset, an antenna, a display, a touchscreendisplay, a touchscreen controller, a battery, an audio codec, a videocodec, a power amplifier, a global positioning system (GPS) device, acompass, an accelerometer, a gyroscope, a speaker, a camera, and a massstorage device (such as hard disk drive, compact disk (CD), digitalversatile disk (DVD), and so forth).

The communication chip 306 enables wireless communications for thetransfer of data to and from the computing device 300. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. The communication chip 306 may implement anyof a number of wireless standards or protocols, including but notlimited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE,GSM, GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well asany other wireless protocols that are designated as 3G, 4G, 5G, andbeyond. The computing device 300 may include a plurality ofcommunication chips 306. For instance, a first communication chip 306may be dedicated to shorter range wireless communications such as Wi-Fiand Bluetooth and a second communication chip 306 may be dedicated tolonger range wireless communications such as GPS, EDGE, GPRS, CDMA,WiMAX, LTE, Ev-DO, and others.

The processor 304 of the computing device 300 includes an integratedcircuit die packaged within the processor 304. In some implementationsof the present description, the integrated circuit die of the processorincludes one or more devices, such as nanowire transistors built inaccordance with implementations of the present description. The term“processor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be stored inregisters and/or memory.

The communication chip 306 also includes an integrated circuit diepackaged within the communication chip 306. In accordance with anotherimplementation of the present description, the integrated circuit die ofthe communication chip includes one or more devices, such as nanowiretransistors built in accordance with implementations of the presentdescription.

In further implementations, another component housed within thecomputing device 300 may contain an integrated circuit die that includesone or more devices, such as nanowire transistors built in accordancewith implementations of the present description.

In various implementations, the computing device 300 may be a laptop, anetbook, a notebook, an ultrabook, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, the computingdevice 300 may be any other electronic device that processes data.

It is understood that the subject matter of the present description isnot necessarily limited to specific applications illustrated in FIGS.1-18 . The subject matter may be applied to other microelectronic deviceand assembly applications, as well as any appropriate transistorapplication, as will be understood to those skilled in the art.

The following examples pertain to further embodiments, wherein Example 1is a nanowire transistor, comprising at least one nanowire channelhaving a first end, an opposing second end, and a top surface; a firstspacer positioned proximate the at least one nanowire channel first endand a second spacer positioned proximate the nanowire channel opposingsecond end; a first hardmask portion abutting the first spacer and thenanowire channel top surface; and a second hardmask portion abutting thesecond spacer and the nanowire channel top surface.

In Example 2, the subject matter of Example 1 can optionally include agate dielectric material abutting the nanowire channel top surfacebetween the first hardmask portion and the second hardmask portion.

In Example 3, the subject matter of Example 2 can optionally include agate electrode material abutting the gate dielectric material.

In Example 4, the subject matter of any of Examples 1 to 3 canoptionally including the at least one nanowire channel comprising aplurality of nanowires channels formed above a microelectronicsubstrate, wherein the nanowire channel are space apart from oneanother; and wherein the first hardmask portion and the second hardmaskportion abutted a top surface of a nanowire channel of the plurality ofnanowire channels which is farthest from the microelectronic substrate.

In Example 5, a method of forming a microelectronic structure maycomprise forming a fin structure on a microelectronic substrate, whereinthe fin structure comprises at least one sacrificial material layeralternating with at least one channel material layer, and hardmask layeron a top surface of the channel material layer farthest from themicroelectronic substrate; forming at least two spacers across the finstructure; selectively removing the sacrificial material layers betweenthe channel material layers to form at least one channel nanowire; andremoving the hardmask layer from between the spacers to leave a portionof the hardmask layer between the spacers and a channel nanowire topsurface farthest from the microelectronic substrate.

In Example 6, the subject matter of Examples 5 can optionally comprisesforming the fin structure on the microelectronic substrate, wherein thefin structure comprises at least one sacrificial material layeralternating with at least one channel material layer, and hardmask layeron the top surface of the channel material layer farthest from themicroelectronic substrate, comprises: forming a microelectronicsubstrate; forming a stacked layer comprising at least one sacrificialmaterial layer alternating with at least one channel material layer;forming a hardmask layer on a top surface of the channel material layerfarthest from the microelectronic substrate; and forming at least onefin structure from the layered stack and the hardmask layer.

In Example 7, the subject matter of any of Examples 5 to 6 canoptionally include forming a sacrificial gate electrode material betweenthe at least two spacers; removing a portion fin structure external tothe sacrificial gate electrode material and the spacers to exposeportions of the microelectronic substrate; and forming a sourcestructure and a drain structure on the substrate portions on opposingends of the fin structure.

In Example 8, the subject matter of any of Examples 5 to 7 canoptionally include forming an interlayer dielectric layer over thesource structure and the drain structure; and removing the sacrificialgate electrode material from between the spacers prior to selectivelyremoving the sacrificial material layers between the channel materiallayers to form the at least one channel nanowire.

In Example 9, the subject matter of any of Examples 5 to 8 canoptionally include forming a gate dielectric material to surround thechannel nanowire between the spacers; and forming a gate electrodematerial on the gate dielectric material.

In Example 10, the subject matter of any of Examples 5 to 9 canoptionally include forming the hardmask layer from a material selectedfrom the group comprising silicon, porous silicon, amorphous silicon,silicon nitride, silicon oxynitride, silicon oxide, silicon dioxide,silicon carbonitride, silicon carbide, aluminum oxide, hafnium oxide,zirconium oxide, tantalum silicate, lanthanum oxide, and polymermaterials.

In Example 11, a method of forming a microelectronic structure maycomprise forming a microelectronic substrate; forming a stacked layercomprising at least one sacrificial material layer alternating with atleast one channel material layer; forming a first hardmask layer on atop surface of the channel material layer farthest from themicroelectronic substrate; forming a second hardmask layer on the firsthardmask layer; forming at least one fin structure from the layeredstack, the first hardmask layer, and the second hardmask layer; removingthe second hardmask layer; forming at least two spacers across the finstructure; selectively removing the sacrificial material layers betweenthe channel material layers to form at least one channel nanowire; andremoving the first hardmask layer from between the spacers to leave aportion of the first hardmask layer between the spacers and a channelnanowire top surface farthest from the microelectronic substrate.

In Example 12, the subject matter of Example 11 can optionally includeforming a sacrificial gate electrode material between the at least twospacers; removing a portion fin structure external to the sacrificialgate electrode material and the spacers to expose portions of themicroelectronic substrate; and forming a source structure and a drainstructure on the substrate portions on opposing ends of the finstructure.

In Example 13, the subject matter of any of Examples 11 to 12 canoptionally include forming an interlayer dielectric layer over thesource structure and the drain structure; and removing the sacrificialgate electrode material from between the spacers prior to selectivelyremoving the sacrificial material layers between the channel materiallayers to form the at least one channel nanowire.

In Example 14, the subject matter of any of Examples 11 to 13 canoptionally include forming a gate dielectric material to surround thechannel nanowire between the spacers; and forming a gate electrodematerial on the gate dielectric material.

In Example 15, the subject matter of any of Examples 11 to 14 canoptionally include forming the hardmask layer from a material selectedfrom the group comprising silicon, porous silicon, amorphous silicon,silicon nitride, silicon oxynitride, silicon oxide, silicon dioxide,silicon carbonitride, silicon carbide, aluminum oxide, hafnium oxide,zirconium oxide, tantalum silicate, lanthanum oxide, and polymermaterials.

In Example 16, the subject matter of any of Examples 11 to 15 canoptionally include forming the second hardmask layer from a materialselected from the group comprising silicon, porous silicon, amorphoussilicon, silicon nitride, silicon oxynitride, silicon oxide, silicondioxide, silicon carbonitride, silicon carbide, aluminum oxide, hafniumoxide, zirconium oxide, tantalum silicate, lanthanum oxide, and polymermaterials.

In Example 17, a computing device may comprises a board including atleast one component; wherein the at least one component includes atleast one microelectronic structure comprising at least one nanowiretransistor including at least one nanowire channel having a first end,an opposing second end, and a top surface; a first spacer positionedproximate the at least one nanowire channel first end and a secondspacer positioned proximate the nanowire channel opposing second ends; afirst hardmask portion abutting the first spacer and the nanowirechannel top surface; and a second hardmask portion abutting the secondspacer and the nanowire channel top surface.

In Example 18, the subject matter of Example 17 can optionally include agate dielectric material abutting the nanowire channel top surfacebetween the first hardmask portion and the second hardmask portion.

In Example 19, the subject matter of Example 18 can optionally include agate electrode material abutting the gate dielectric material.

In Example 20, the subject matter of any of Examples 17 to 19 canoptionally including the at least one nanowire channel comprising aplurality of nanowires channels formed above a microelectronicsubstrate, wherein the nanowire channel are space apart from oneanother; and wherein the first hardmask portion and the second hardmaskportion abutted a top surface of a nanowire channel of the plurality ofnanowire channels which is farthest from the microelectronic substrate.

Having thus described in detail embodiments of the present description,it is understood that the present description defined by the appendedclaims is not to be limited by particular details set forth in the abovedescription, as many apparent variations thereof are possible withoutdeparting from the spirit or scope thereof.

What is claimed is:
 1. A method of forming a microelectronic structure, comprising: forming a plurality of channel material layers over a microelectronic substrate, forming a sacrificial material layer between two of the plurality of channel material layers, forming a hardmask layer on a top surface of a first channel material layer of the plurality of channel material layers, wherein the first channel material layer is the farthest of the plurality of channel material layers from the microelectronic substrate; forming spacers on at least a part of the hardmask layer; selectively removing the sacrificial material layer between the two channel material layers to form a nanowire channel from the plurality of channel material layers, wherein the hardmask layer protects the first channel material layer during the selectively removing of the sacrificial material layer; selectively removing the hardmask layer from between the spacers after selectively removing the sacrificial material layer between the two channel material layers to leave a portion of the hardmask layer within the spacers and on top of a nanowire channel top surface farthest from the microelectronic substrate; forming a source structure and a drain structure over the microelectronic substrate on opposing ends of the plurality of channel material layers, forming a gate dielectric material to surround the nanowire channel between the spacers, and forming a gate electrode material on the gate dielectric material, wherein, the hardmask layer comprises at least one material selected from a group consisting of silicon, porous silicon, amorphous silicon, silicon nitride, silicon oxynitride, silicon oxide, silicon dioxide, silicon carbonitride, silicon carbide, aluminum oxide, hafnium oxide, zirconium oxide, tantalum silicate, lanthanum oxide, and polymer materials.
 2. The method of claim 1, wherein the nanowire channel comprises silicon germanium.
 3. The method of claim 1, wherein the nanowire channel comprises silicon.
 4. The method of claim 1, wherein the source structure and the drain structure comprise n-doped silicon.
 5. The method of claim 1, wherein the source structure and the drain structure comprise p-doped silicon.
 6. The method of claim 1, wherein the source structure and the drain structure comprise p-doped silicon germanium.
 7. The method of claim 1, further comprising: forming a sacrificial gate electrode material between the spacers.
 8. The method of claim 7, further comprising: forming an interlayer dielectric layer over the source structure and the drain structure; and removing the sacrificial gate electrode material from between the spacers prior to selectively removing the sacrificial material layer between the channel material layers to form the nanowire channel.
 9. The method of claim 8, wherein the nanowire channel comprises silicon germanium.
 10. The method of claim 8, wherein the nanowire channel comprises silicon.
 11. The method of claim 8, wherein the source structure and the drain structure comprise n-doped silicon.
 12. The method of claim 8, wherein the source structure and the drain structure comprise p-doped silicon.
 13. The method of claim 8, wherein the source structure and the drain structure comprise p-doped silicon germanium.
 14. The method of claim 1, wherein the gate electrode material comprises a metal carbide.
 15. The method of claim 14, wherein the metal carbide comprises a material selected from the group consisting of titanium carbide, zirconium carbide, tantalum carbide, and tungsten carbide.
 16. The method of claim 1, wherein the gate electrode material comprises a metal oxide. 